Used AT as purchase platform for a Facebook Marketplace deal
I bought a car sight unseen on facebook marketplace, and used Autotrader PrivateSeller to ensure the purchase was safe (title transfer, guaranteed car in hand, etc.). The seller just listed the vin on auto trader for me to make an offer on to which they accepted. I chose to set up my own shipping as well which went fine. Would do the process the same way if it comes up again.
